Analysis of the Relation between State of Health and Self-Discharge of Li-Ion Batteries

Abstract

Li-ion batteries have become a widespread solution for modern energy storage systems, both for e-mobility and stationary storage. SOC and SOH estimation of batteries has great importance from both technical and economic aspects. There are many ways to estimate SOC and SOH with different complexity and accuracy rates, our paper focuses mostly on SOH. At first, this paper gives a brief review of possible methods of SOH determination. From these methods, one way is developed to measure an indicator related to SOH, and from the indicator estimating it. In our paper, we analyzed the connection between SOH and self-discharge for different time periods. The capacity degradation was measured with a high current, that closely resembles modern e-mobility applications. After that, from our experimental data, with the measured self-discharge, the final best-estimated SOH value in the range of ± 3% is achieved.